This Standard specifies classification and code, order information, size, appearance and weight, technical requirements, test methods, inspection rules, packaging, marks and quality certificate of quality carbon structural steel bars. This Standard is applicable to hot-rolled or forged quality carbon structural steel bars of which nominal diameter or thickness is not greater than 250 mm. Hotrolled or forged quality carbon structural steel bars of which nominal diameter or thickness is greater than 250 mm shall also be supplied, as agreed between the buyer and the supplier.